Commodity sales data, which is accumulated in a POS terminal or the like every day, accurately reflects the state of sales at the relevant store and thus provides material very helpful in plotting a sales strategy. For this reason, the value of commodity sales data has been highly increased in the retail trade and the like operating supermarkets or the like.
As the value of commodity sales data is increased as mentioned above, more and more wrongdoers have attempted to improperly run away with commodity sales data from a POS terminal. Common POS terminals are identical with PCs in configuration. Therefore, many of them are provided with a data transmitting and receiving unit (for example, USB port) to which a storage device (for example, USB memory) can be connected. It is easy to connect a storage device to a POS terminal and copy and run away with commodity sales data.
In stores, such as supermarkets, one POS terminal is operated by multiple users as a rule. Therefore, even though it is revealed that an unjustifiable act has been carried out and an attempt is made to find out the wrongdoer, it is very difficult.
Japanese Unexamined Patent Publication No. 2007-148762 discloses a technique for making a specific PC unusable unless a specific storage device is connected to the PC. If this storage device is stolen by a wrongdoer, however, it is impossible to find out the true criminal.